Exit codes

Karafka supports three exit statuses:

• 0 - in case shutdown was smooth and everything was as expected (all the work was done, consumers stopped, etc.).
• 1 - Ruby exit code for syntax errors and any other boot problems.
• 2 - in case there was a forceful shutdown in which not all consumers finished their work. This can happen when you set up shutdown_timeout but your processing takes longer than that.